Silicon Oxide Li-Ion Anode Electrolyte for Thermal Runaway Resistance
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Solution Overview
Problem
Lithium ion secondary batteries using high-capacity silicon-based negative electrode active materials face safety concerns due to potential thermal runaway from uncontrollable stored energy.
Innovation Solution
A lithium ion secondary battery design that incorporates a negative electrode active material containing silicon oxide and a compound with a first element, such as potassium (K), sodium (Na), magnesium (Mg), or zinc (Zn), along with an electrolytic solution containing an imide salt with the same first element, to enhance safety by forming a resistance layer that inhibits internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-capacity silicon-based negative electrode active material is used, then the battery capacity increases, but thermal runaway risk increases due to uncontrollable stored energy
Solution Approach 1:
A coating layer containing the first element is formed on the silicon oxide particles before electrode assembly. This preliminary coating prevents direct contact between silicon oxide and electrolyte, and enables controlled reaction to form protective resistance layers during initial charging cycles, preventing subsequent thermal runaway
Solution Approach 2:
The first element acts as an intermediary substance between silicon oxide and the electrolyte. It reacts with oxygen to form a resistance layer that mediates the interaction, preventing direct harmful reactions while allowing controlled lithium ion insertion. The imide salt in electrolyte continuously replenishes the first element at the electrode surface
2Quantity of substance
If silicon oxide is used as negative electrode active material, then higher capacity is achieved, but safety deteriorates due to potential internal short circuits
Solution Approach 1:
The resistance layer is formed locally at the surface of silicon oxide particles where it contacts the electrolyte. This localized protective layer has different properties (high resistance) from the bulk silicon oxide, providing safety without compromising the high capacity of the bulk material
Solution Approach 2:
The negative electrode active material is composed of a composite structure: silicon oxide core particles coated with compounds containing the first element. This composite structure combines the high capacity of silicon oxide with the protective properties of the coating layer, achieving both performance and safety
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed battery design achieves excellent safety by preventing thermal runaway through the formation of a resistance layer, which is sustained by continuous supply of the first element from the electrolytic solution, thereby ensuring stable operation even under conditions of high energy storage.
Implementation Method 1
the formation of a resistance layer, which is sustained by continuous supply of the first element from the electrolytic solution
Implementation Method 2
continuous supply of the first element from the electrolytic solution
Data Source
AI summary
A lithium ion secondary battery includes: a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material which contains silicon oxide and a compound containing a first element. The electrolytic solution contains an imide salt which contains the first element and an imide anion. The first element is any one or more elements selected from the group consisting of K, Na, Mg, Ca, Cs, Al, and Zn.